Armature keeps spinning around root bone in pose mode when I try to move anything
This spinning effect many times is caused by an incorrectly set up IK constraint. Please check the Tutorial again for two things:


to which bone is the target of the IK chain parented to? The target is the bone which you actually move by hand. It must not be a child of the bone chain which is deformed by the constraint
what is the chain length in your IK constraint? By default it is set to 0, meaning the IK constraint affects every bone in the hierachy, so each bone which is a parent of the bone which holds the constraint. Try setting it to 2 for a start and check the deformation. Chain length is the number of bones which are affected by the constraint, including the bone which holds the constraint